A number of approaches are available to assist a vehicle in maintaining a central position within a driving lane. One such approach is generally referred to as a lane keeping system that includes a camera for gathering information regarding the position of the vehicle within the driving lane. For example, in one approach the lane keeping system may calculate a corrective steering torque that is a function of error between a target lane keeping position and an estimated position of the vehicle within the driving lane. The corrective steering torque is superimposed with a steering assist torque that is provided to a handwheel.
The current approach of calculating the corrective steering torque may have several limitations. For example, the application of the corrective steering torque may result in either an under-correction or an over-correction of the handwheel, depending on the amount of torque the driver is applying to the handwheel and the steering assist torque. Thus, a sensor or command switch may be provided for detecting whether a driver's hands are present on the handwheel. However, drivers tend to have varying grip levels on the handwheel.
Another limitation is that there are challenges in determining the appropriate limit of the corrective steering torque that may be applied to the handwheel. For example, if the corrective steering torque is applied to an input of an assist algorithm, then performance variations may occur. If the corrective steering torque is applied to an output of an assist algorithm, then variation in the handwheel torque may be less predictable. As a result, the corrective steering torque limits may be exceeded. Also, the constant application of the corrective steering torque may negatively impact the overall steering feel of the handwheel. This is because the corrective steering torque is generally applied even as a driver is steering through maneuvers.